Mineralogic composition of cryogenic evaporites determined by low-temperature X-ray diffactometry

As part of a collaborative investigation between researchers at Rice University, Arkansas State University,
University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth
intervals during the 2005-2006 field season. Sample splits were subsequently analyzed for chemical and isotopic
composition of both gases and dissolved ions, as well as dissolved organic carbon. In addition, cryogenic salts were
sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and
in the case of Lake Vanda, a white precipitate was recovered from the lake bottom. Presented in this file is the mineralogic composition of salt crusts that were collected on the surface
of sediment and rocks surrounding the lakes, as well as the lake-bottom precipitate from Lake Vanda. The results
are based on low-temperature XRD determinations, and Rietveld refinement of whole peaks.